Assessment of the impact of plant species composition and drought stress on survival of strongylid third-stage larvae in a greenhouse experiment.

Grazing livestock is always exposed to infective parasite stages. Depending on the general health status of the animal, the farm management, environmental conditions and pasture exposure, the impact ranges from non-affected to almost moribund animals. The greenhouse experiment was performed to investigate how climatic changes and plant composition influence the occurrence/survival of strongylid third-stage larvae (L3) on pasture.

N-nitrososdimethylamine is activated in microsomes from hepatocytes to reactive metabolites which damage DNA of non-parenchymal cells in rat liver.

The liver carcinogen N-nitrosodimethylamine (NDMA) has to be metabolically activated by specific cytochromes before it can react with cellular macromolecules (e.g. proteins or DNA).

[Genotoxic effect on human mucous membrane biopsies of the upper aerodigestive tract].

Background: In numerous epidemiologic studies, environmental and occupational substances such as sodium dichromate (Na2Cr2O7), benzo[a]pyren (B(a)P), and N'nitroso-diethanolamine (NDELA) have been shown to be of potential carcinogenic risk on human epithelial cells in the upper aerodigestive tract.

Methods: Using the alkaline microgel electrophoresis technique (comet assay). mucosal cells isolated from biopsies of the upper aerodigestive tract (nose, paranasal sinuses, mouth, pharynx, larynx, and tonsils) were used to analyze target sites for different genotoxic substances and specific sensitivities of each donor.

Genotoxic bifunctional aldehydes produce specific images in the comet assay.

Seven genotoxic aldehydes (acrolein, chloroacetaldehyde, crotonaldehyde, formaldehyde, glutardialdehyde, glyoxal, and methylacrolein) have been studied in vitro using the alkaline version of the comet assay (or single cell microgel electrophoresis assay) in freshly isolated rat hepatocytes. Chloroacetaldehyde, glyoxal and methylacrolein treatment resulted in an elevated tail moment (TM), used as indicator for an DNA damaging activity and formation of comet like structures. In addition, this treatment also caused characteristic DNA spot images with small, highly condensed areas within the otherwise circular DNA spots.

In vivo studies on genotoxicity of pure and commercial linuron.

The ureic herbicide linuron [3-(3, 4-dichlorophenyl)-1-methoxy-1-methylurea] (CAS 330-55-2) was investigated for genotoxicity in a series of in vivo experiments. Since human exposure to herbicides is not only to the active principles, but also to all the chemicals present in the commercial formulation, we tested both pure and commercial linuron. Groups of rats were treated with gavage containing different doses of the herbicide (pure compound or commercial formulation) for 14 days.

Transport of reactive metabolites of procarcinogens between different liver cell types, as demonstrated by the single cell microgel electrophoresis assay.

Procarcinogens have to be activated by specific cytochromes before showing adverse effects. Freshly isolated hepatocytes (parenchymal liver cells, PC) are characterized by a high content of such xenobiotic enzymes and are widely used to investigate chemically induced DNA damage. But in many cases liver tumors caused by indirect acting carcinogens can also originate from non-parenchymal liver cells (NPC).

Detection of genotoxic effects in human gastric and nasal mucosa cells isolated from biopsy samples.

To assess genotoxic burdens from chemicals, it is necessary to relate observations in experimental animals to humans. The success of this extrapolation would be increased by including data on chemical activities in human tissues. Therefore, we have developed techniques to assess DNA damage in human gastric and nasal mucosa (GM, NM) cells.

Systemic genotoxic effects of tobacco-related nitrosamines following oral and inhalational administration to Sprague-Dawley rats.

An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion.